Matrix dot wire printers have been in use for some years and often include a circular arrangement of electromagnets which are selectively energized to attract a cylindrical movable core mounted intermediate opposite ends of a print wire actuator lever. The magnetic gap between the fixed core and the movable core is small but provides a longer stroke to the print wire because of the mechanical advantage provided by the pivoting actuator lever. Examples of this general type of dot printer head are disclosed in U.S. Pat. Nos. 3,770,092; 3,892,175; and 4,244,658.
The actuator levers of the prior art type of dot printer are pivotally supported at their outer ends and extend inwardly across the electromagnetic coils with the inner ends of the actuator levers engaging the ends of the print wires and moving them toward a print position when the corresponding electromagnetic actuator is energized. When the cylindrical movable core moves into and out of the electromagnetic coil, it follows an arcuate path of movement in the cylindrical bore in the electromagnetic coil or actuator. In prior art types of dot printer heads, the pivotal support of the actuator lever is provided in a plane which is normal to the cylindrical bore and positioned above the open end of the cylindrical bore in the electromagnetic actuator so that a substantially large circumferential clearance must be provided between the outer periphery of the cylindrical movable core and the inner periphery of the cylindrical bore of the electromagnetic actuator. This large clearance reduces the electromagnetic efficiency of the print actuator. This reduced efficiency in turn tends to adversely affect the size of the print head, the energy it requires, and the heat it genertates in operation.